The invention relates to a fluid pump for pumping liquid and/or gas phase materials. The fluid pump is useful, as described in my earlier applications, in the context of an output system of an internal combustion engine or a turbine engine and an input system for injecting fluid into the combustion process. The input system, in that case, includes a displacement pump, specifically for use with air and water, which can be utilized as a gas compression pump in the internal combustion engine and the turbine.
Fluid displacement pumps are subject to a variety of applications in engineering. For instance, such pumps are utilized in compression systems such as air compressors and as fluid pumps. For example, British Patent Specification 265,659 to Bernhard discloses an internal combustion engine with fuel pressurization separate from the combustion chamber. There, fuel is pressurized in a compressor and the pressurized fuel is fed from the pump to the engine through a port assembly.
U.S. Pat. No. 1,287,268 to Edwards discloses a propulsion system for a motor vehicle. There, a compressor formed with mutually interengaging helical impellers pumps to an internal combustion engine which is also formed with mutually interengaging helical impellers. The internal combustion engine drives a generator, which pumps hydraulic fluid to individual hydraulic motors that are disposed at each of the wheels. The impellers of Edwards are formed with xe2x80x9cflatxe2x80x9d blades of a constant thickness from the axle radially outward to their outermost tip.
The efficiency of fluid pumps with interengaging impeller blades is dependent on the seal that is in effect formed between the blades. While the outer seal is relatively easily obtained with a corresponding housing wall, the inner seal between the blades, i.e., at the location where the blades overlap is rather difficult to obtain. In the prior art system of Edwards, for example, the flat blades do not sufficiently seal against one another and the corresponding efficiency of the double impeller pump is therefore relatively low. Certain applications of the fluid pump require a better seal and better backflow prevention.
It is an object of the invention to provide a fluid displacement pump, which overcomes the disadvantages of the heretofore-known devices and methods of this general type and which is further improved in terms of efficiency and backflow prevention, and which allows essentially continuous pumping output with negligible backflow.
With the foregoing and other objects in view there is provided, in accordance with the invention, a fluid displacement pump, comprising:
a housing formed with a chamber having a wall defined by two parallel, mutually intersecting cylindrical openings defining respective cylinder axes; and
two axles respectively disposed at and rotatably mounted about respective axes coaxial with said cylinder axes, said axles each carrying a helically rising blade sealing against said wall of said housing and engaging into one another so as to form a substantially completely closed wall within said chamber during a rotation of said axles;
said blades having a decreasing thickness from said axles to an outer periphery thereof.
In an alternative embodiment of the invention, the blades increase in thickness from the axle outward. Details of the alternative embodiment will emerge from the following description of the figures.
In accordance with an added feature of the invention, said blades have a rounded surface extending from said axle to an outer periphery thereof.
In accordance with an additional feature of the invention, said rounded surface is defined by a radius of curvature in a radial section of said blades, said radius being greater than a diameter of said blades. Preferably, the radius of curvature is approximately three times the diameter of said blades.
In accordance with another feature of the invention, said blades are trapezoidal as seen in axial section, with mutually opposite surfaces steadily merging towards one another from said axle to the outer periphery.
With the above and other objects in view there is also provided, in accordance with the invention, a fluid displacement pump, comprising:
a housing formed with a chamber having a wall defined by two parallel, mutually intersecting cylindrical openings defining respective cylinder axes; and
two axles respectively disposed at and rotatably mounted about respective axes coaxial with said cylinder axes, said axles each carrying a helically rising blade sealing against said wall of said housing and engaging into one another so as to form a substantially completely closed wall within said chamber during a rotation of said axles;
said blades having a given thickness and helically rising along said axle with a given lead substantially greater than the given thickness of said blades.
In a preferred embodiment, the ratio of the spacing between the blade turns (the lead minus the blade thickness) to the thickness of the blades lies between 5/4 and 2.
The axles are preferably cylindrical, i.e., their peripheral wall is defined by mutually parallel lines.
In accordance with an added feature of the invention, the rounded surface is defined by a radius of curvature in a radial section of the blades, the radius being greater than a diameter of the blades. In a preferred embodiment, the radius of curvature is approximately three times the diameter of the blades.
In accordance with another feature of the invention, the blade on each of the axles has a rise angle along the helix of approximately 7xc2x0 and the blades are substantially trapezoidal in radial section from the axle to a periphery thereof.
In accordance with again an added feature of the invention, the blade of one helix of the double helix are spaced apart by a distance defined by the blades of the other helix of the double helix.
In accordance with a concomitant feature of the invention, the blades enclose an angle of between approximately 45xc2x0 and almost 90xc2x0 with the cylinder axes.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a fluid displacement pump with backflow stop, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.